Insecticidal composition containing pyrethrins and a synergist therefor



Patented May 1, 1Q51 ING PYRETHRINS THEREFOR AND: A. srnnnmsm Hermanwachs, Brooklyn, N. Y., assignor te -U: S,

Industrial Chemicals, Inc., New York, N. Y., a;

corporation of Delaware Application February 21, 1949, SerfaLNo. 77,686

I lii -Glaiinsj (01.167-24) V o lk ew r This invention relates toinsecticidal compositions containing pyretlirins and a synergisttherefor.

Out of all the insecticidamaterials in use, the one which approachesmost" nearly the ideal is pyrethrum flowers-or, rather, the activeinsecticidal principle, Dyrethrins, which appear in thepyrethrumflowers. Pyrethrins are immediately toxic to avery great numberof. insect pestsatr different concentrations varying with theresist anceof the insects mentioned Also. they; are.

' substantially non-toxic to animals: and plants.

The endeavor to extend the usefulness of; pyrethrins by increasing,their effectiveness and lowering their cost has led toextensive researchon another class of, insecticide materials-custom: arily referred to assynergistsl As-the WOIFd: synergists is generally understood, such mayor tion t provide a novel insecticidal compositioii' containingpyfiethmhsindie y ergist therefor,

the composition being substantially non-toxic and: non-injuriousto:both: animals and, plants; at least tozganwextent. whichv permits thcil?pracs tically unrestricted: use-i It is also an:- obj'ectot. thepresent. invention! to; provide: such compositions whichmay contain arelatively small percentage: Of; pyrethrins withe out loss of emciencyand in: some-instances with a donsiderablegairr inaefliciency.

lflllShBdllIl" accordance-with; thepresen't inventiom may not haveappreciable insecticidal value when used' by themselves-,butwhen used incombinat-ion' with suitable quantities of; some:- other insecticidalsubstance suchas pyrethrins, the. resultant insecticide. has: an;effectiveness. ap preciably greater than would bezcalculatedl from;the-sum total of its; constituents; It may: be." said that synergism orsynergistic action has occurred when the above condition is met.

The mechanism of synergism is by no means understood on thebasis ofpresent knowledge? It is not only possible but probable, that it differsin the case of different synergistic combina tions.

The application of synergists in the problems connected with pyretlirunrinsecticides-has received particular attention both because of therecognizably unique value of pyrethrins and because. their.relativelyhigh: cost, has encouraged study of methods to extend theirusefulness and reduce the cost. of. insecticides made= from them. Manysubstances have: been: found;- possessing; more on less synergisticvalue when used: with pyrethrins, but these known synergistssares far asI am: aware, deficientin two important respects; First, while? theiruse: does exteridrthe killing; power of the pyrethrins: andi permitseflfective insecticides to be made having, lower pyrethrin content than:would otherwise be? the case, it is? still necessary that thepyrethrin-i cons tent. be substantially high. Secondly,theses'ynergists: have displayed marked specificity in that. while theymay;- increase the killing power: on Pylethrins against some varietiesof insects to; a marked extent, they have been: found; be. relativelyinefiective in-the: case of. other: and; more numerous varietiesofl'inseictss. 2 I s The foregoing; being: in: brief. the state-or theartgihis theretoream obiectlofithapresentinvens It: is; a further?object:- or this invention to pro vide such compositions which are markdly su pe'rior in theirfreedom from specificity,

The foregoing and. other objects? are accom-r,

by: preparing-e a: composition containingapyrethnins: and as. a;synergist'therefor a-compound of the? generic: formula: a l

in which R is a saturated, bivalent, aliphatic, hydrocarbon radicaLA isthe hydrogen atom or an nryrranisat R'"is an alkyl, cycloalkyl, aralkyl,aryl or heterocyclic radical, A" is a saturated, bivalent, aliphatic,hydrocarbon radical havin from two to thrus carbon atoms and n is aninteger from one to three. 1 Thus, in the preceding generic formula, B.may be, for example, the methylene radical; A may be, for example, themethyl, ethyl, n-propyl, etc. radical; R may be, for example, themethyl, ethyl, n-propyl, i-propyl, v n-butyl, tert.-butyl, mnexyucyc'1chexyipneny1,"o tolyl mac-13,1, p tolyl;benzylitetrahycrofurrury-n. etczradicals and A may bearer enample,thethylenavpro pylene, etc. radical. The compounds of the aforementionedgenenic': formula may be prepared as is described in my copendingiapplication, Serial No. 729,883, filed February 2.0; 1947, Patent No.2,485,681, of which application the present application is acontinuation-in-part.

For exampl'a- 'tlle compounds: of the arms eenerimmrmui m y Be prepareuby-th'e reac es of a halide (e: g1, a chloride? of the gerreric fcrmula1 in which A, A and n have the meaning above indicated; or by thereaction'of the sodium salt of the hydroxide of a compound having thegeneric formula.

with a halide (e. g., formula a chloride) having the genericC1-[A'0-'-lnR' In conducting both of the aforementioned reactions, asodium halide (e. g., sodium chloride) is formed in addition to thesynergist used in accordance with the present invention.

' The monoglycol or polyglycol ethers, used in the preceding reactionsin the form of their halides or sodium saltsin making the synergist,include ethers of monoethylene glycols and polyethylene glycols, as wellas higher alkylene monoglycols and polyglycols and include themonomethyl ether of monoethylene gylcol, the monoethyl ether ofmonoethylene glycol, the mono-n-butyl ether of monoethylene glycol, themonophenyl ether of monoethylene glycol, the z-ethylbutyl ether ofmonoethylene glycol, the monomethyl ether of .diethylene glycol, themonoethyl-ether of diethylene glycol, the monon-butyl ether of ethyleneglycol, the mono-2- ethylbutyl ether of diethylene glycol, the monoethylether of triethylene glycol, the monoethyl ether of propylene glycol,the monobutyl ether CHr-CHz-CH as described in Beilstein 19, 27 (1934).

Alcohols havingthe generic formula CHr-CHr-CH-R" in which R" is an alkylgroup, such as the of dipropylene glycol, the monobutyl ether of 7di-trimethylene glycol, etc.

n-propyl, n-butyl, n-hexyl, 2-ethylhexyl, etc. radical, or a cycloalkylgroup, such as the cyclohexyl radical, can be prepared by reduction ofthe unsaturated ketonesof the generic formula Example I 'A particularlyvaluable product for use as a synergist for pyrethrins is obtained whena chloromethyl derivative of dihydrosafrol is reacted with the sodiumsalt of the mono-nbutyl ether of diethylene glycol to form an etherderivative as illustrated by the following equation:

o cm-cm-cn. NaO-GHz-CIEh-O-OH -CH -OOJI. Hi0 p v o cm-cm-cn. NaCl mo Thechlorides or other halides containing the methylenedioxyphenyl radicalinclude the chloromethyl derivative of dihydrosafrol CHr-CHr-CH;

CHgCl Y enedioxyphenyl group. Dihydrosafrol, which was mentioned above,is a, compound having the structural formula.

The preparation of the synergist is illustrated by the followingexample:

22 parts of sodium hydroxide pellets were added to-162 parts of themono-n-butyl ether of diethylene glycol in parts of benzene, and themixture was refluxed using a water trap until no more water wascollected (approximately 18 hours).

The solution was cooled, and under continued cooling 106 parts ofchloromethyl dihydrosafrol in 45 parts of benzene were added. Afterstanding overnight, the mixture was refluxed for four hours. The pelletwhich separated was removed by washing with water, the separated benzenesolution was dried, and the benzene was distilled off. The remaining oilwas thereafter distilled under a vacuum. During the-vacuum distillation,some of the excess mono-n-butyl ether of diethylene glycol distilledassure? 1931.61 first, after which the final product distilled iataabout195 at 2 rnm. of mercury pressure. The product was a colorless {011,soluble in benzene, isopropyl alcohol and most organic solvents.

The resultingproduct was a valuable synergist for pyrethrins. When usedwith pyrethrins in the proportions of 30 mg. of pyrethrins and 30.0 mg.of the synergist dissolved in 2100 ml. of odorl ss ke o e n insect sprayw pr duc which gave practically complete knockdown and kill of flies.

Example II Eacample III Instead of using the sodium salt of themonon-butyl ether of diethylene glycol as in Example I, an equivalentamount of the sodium salt of the mono-n-butyl ether of ethylene glycolwas used, and the resulting synergist boiled at about 167 C. at 2 mm. ofmercury pressure. 1,000 mg. of this product and 30 mg. of pyrethrinsdissolved :in 100 ml. of odorless kerosene gave a knockdown of 96% and akill of 86% "in the Peet- Grady test, while the O. T. I. was-96% and54%, respectively.

Example IV Instead of using the sodium salt of the mono-.- n -jbutylether of diethylene glycol as in Example I, an equivalent amount of thesodium salt of the monobenzyl ether of vmonoethylene glycol was used,yielding a synergist boiling at 195-205 C. at 1.5 mm. of mercurypressure. 300mg. of this product and 30 mg. of pyrethrins in 100 ml. ofodorless kerosene gave a knockdown of 98% and a. kill of 76%, the O. T.I. giving 96% and 54%, respectively.

' Example V Instead of using the sodium saltof the monon-butyl ether ofdiethylene glycol as in Example I, an equivalent amount of the sodiumsalt of the monomethyl ether of diethylene glycol was used, giving asynergist boiling at 168 QC. at" 0. 4 mm. ofrmercury pressure. 300 mg.of this product and 30 mg. of pyrethrins in 100 ml. of odorless kerosenegave a knockdown of 99% and a kill of 94%, while the O. T. I. was 99%and 54 respectively. j 5

Example VI 61 parts of the mono-nebutyl ether of diethylene glycol wasdissolved in 45 parts of benzene.

11 parts of sodium hydroxide pellets were added, and the mixture wasrefluxed using a water ftrap condenser until .no. more water wouldcollect (boiling overnight was sufiicient). The benzene solution wasthen cooled, and under continued cooling with ice water 49.5 parts ofisosafrol hydrochloride (1- (3,4-methyl-enedixoyphenyl) l-chloropropane)in 45 parts of benzene was added. After standing overnight, the mixturewas refluxed for four hours. The mixture was '6 then washed with 'wvaterto remove the sodium chloride formed, after which the benzene ,wasdistilled oif and the remaining product 'was dis.- t'illed using avacuum. The final product boiled at 210-216" C. at '7 mm. of mercurypressure.

A solution of 300 mg. of thisproduct and 30 mg. of pyrethr'ins dissolvedin ml. of deodorlized jkerosene gave .a knockdown of 97% in 1 0 minutesand a kill of 97%. The marked synergis'tic elfec't of the synergistisindicated by the fact that a solution of 13.0 mg. of pyrethrins 100 ml..of deodorized kerosene gave a kill of less thanZD 1%., while a solutioncontaining 300 mg. of the synergist 'ini'100 .ml. ofkerosenegavepractically no "knockdown.

Example VII 28.5 ,partsof monomethyl ether .of rmonoethyl- Bne glycolwas dissolved in 45 parts of benzene, 17 parts of sodium hydroxidepellets were added and this mixture'was refluxed using a water trapcondenser until no more water would collect. The-benzene solution wascooled, and under cooling with ice water 49.5 parts or isosafrolhydrochloride in 45 parts of benzene was added. .After standingovernight, the mixture was refluxed for four hours, was washed withwater to remove the sodium chloride formed, the benzene was distilledoff, and the remaining product was distilled using a vacuum. The finalroduct boi-led at -168? G.:.at.1;5 mm. of "mercurypressure.

300mg. 'of this product and '30 mgof pyrethrins in .100 .ml. of:deodor-ized kerosene ;gave a knockdown of 99% and a kill "of 88% whentested according to the Feet-Grady method.

Enample VIII tion is readily soluble in liquids of the Freon type, suchas Freon 12 methyl chloride, etc, which are gases at ordinary pressuresand are used as propellants for'insecticides. Thefollo'wing example willillustrate the effectiveness of suchsolutions.

Example IX A solution containing 600 mg. of pyrethrins under certaintest conditions gave a knockdown of approximately 85% in 10 minutes "anda kill of 46%. A similar solution containing 600mg. of pyrethrins and1000 mg. of the synergist described in Example VI above gave a knockdownof 97.5% and a kill of 97.5%.

The-synergistic mixture may also be used as the active ingredient ofinsecticidal dusts. Thus, a dust base containing 2.5% of the synergistand 0.2% ofpyrethrins may be prepared by incorporating the requiredingredients into a carrier, such as exhausted pyrethrin flowers (aby-product of the pyrethrin extract manufacture). This dust base may befurther diluted with three or four parts of an inert carrier, such astalc, and

the resulting dust is active against a wide variety 7 of insects.

Example X I Piperonyl bromide was reacted with the sodium "salt of themonomethyl ether of ethylene glycol to yield a liquid boiling at142.5144.5 C. at 3.7 mm. of mercury pressure. 300 mg. of this productand 30 mg. of pyrethrins dissolved in 100 ml. of odorless keroseneshowed a kill of 43% in the Peet-Grady Chamber, as compared with a killof 52% for the I. I. While this result is considerably poorer than theresults obtained with many of the other synergists employed in accord-.ance with the present invention, the result nevertheless definitelyshows that the synergist 'adds considerably to the insecticidal activityof the pyrethrins.

Example XI Example XII Piperonyl bromide was reacted with the sodiumsalt of the monophenyl ether of monoethylene glycol to yield a productwhich was a liquid boiling at 167 C. at 0.4 mm. of mercury pressure. 300

.mg. of this product and 30 mg. of pyrethrins in 100 ml. of odorlesskerosene gave a kill of 46%, as compared with a kill of 52% for the 0*.T. I.

Example XHI 1-(3,4- methylenedioxyphenyl) 3 bromopropane was reactedwith the sodium salt of the mono-n-butyl ether of monoethylene glycol toyield a product which boiled at 165-171 C. at 0.7 mm. of mercurypressure. 300 mg. of this product and 30 mg. of pyrethrins in 100 ml. ofodorless kerosene gave a kill of 90.5%, as compared with a kill of 52%for the 0-. T. I.

Example XIV In Example XIII, the mono-n-butyl ether of diethylene glycolwas substituted for the monon-butyl ether of monoethylene glycol. Theproduct boiled at 182 C. at 0.7 mm. of mercury pressure. 300 mg. of theproduct and 30 mg. of pyrethrins in 100 ml. of odorless kerosene gave akill of 92%, as compared with a kill of 52% for the O. T. I.

Reference is made to my copending application Serial No. 688,967, filedAugust 7, 1946, later formally abandoned.

I claim:

1. An insecticidal composition comprising pyrethrins and as a synergisttherefor a compound of the generic formula R[ OA-1,. 0 R

in which R is a saturated, bivalent, aliphatic, hy-

drocarbon radical, A is a substituent selected from the group consistingof the hydrogen atom' and alkyl radicals, R is a substituent selectedfrom the group consisting of alkyl, cycloalkyl, aralkyl, arylandheterocyclic radicals, A is a saturated, bivalent, aliphatic,hydrocarbon radical having from two to three carbon atoms and n is aninteger from one to three.

2. An insecticidal composition comprising pyrethrins and as a synergisttherefor a compound of the generic formula in which R is a substituentselected from the group consisting of alkyl, cycloalkyl, aralkyl, aryland heterocyclic radicals, and n is an integer from one to three.

3. An insecticidal composition as in claim 2 in which R is an alkylradical.

4. An insecticidal composition as in claim 2 in which R is the n-butylradical and n is two.

5. An insecticidal composition comprising pyrethrins and as a synergisttherefor a compound of the generic formula CHrCHr-CH in which R is asubstituent selected from the group consisting of alkyl, cycloalkyl,aralkyl, aryl and heterocyclic radicals, and n is an integer from one tothree.

6. An insecticidal composition as in claim 5 in which R. is an alkylradical.

7. An insecticidal composition as in claim 5 in which R is the n-butylradical and n is two.

8. An insecticidal composition comprising pyrethrins and as a synergisttherefor a compound of the generic formula in which R is a substituentselected from the group consisting of alkyl, cycloalkyl, aralkyl, aryland heterocyclic radicals, and n is an integer from oneto three.

9. An insecticidal composition as in claim 8 in which R is an alkylradical.

10. An insecticidal composition as in claim 8 in which R is the n-butylradical and n is two.

HERMAN WACHS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,421,569 La Forge et a1 June 3,1947 2,431,844 Synerholm Dec. 2, 1947 2,452,188 Hedenburg Oct. 26, 19482,457,957 Wachs Jan. 4, 1949

1. AN INSECTICIDAL COMPOSITION COMPRISISNG PYRETHRINS AND AS A SYNERGISTTHEREOF A COMPOUND OF THE GENERIC FORMULA